Comparison of Canon EF 16-35mm f/2.8L USM and Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM

Attribute	Canon EF 16-35mm f/2.8L USM ×	Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM ×
Filter Size (mm)	77	77
Notes	Includes Hood EW-83E, Lens Case LP 1319	Available AF Mounts: [HSM version]: Sigma, Canon, Nikon; [w/o HSM]: Minolta, Pentax
Closest Focus (m)	0.28	0.27
Magnification Ratio (x)	0.22	0.22
Type	Wide Zoom	Wide Zoom
Length (mm)	103	88.7
APS Equivalent	26 - 56mm	1.5x: 25.5 - 52.5mm; 1.6x: 27.2 - 56mm
Zoom System	Rotary	Rotary
Image Circle	35mm	35mm
Focal Length (mm)	16.00 - 35.00	17.00 - 35.00
Brand	Canon	Sigma
Name	Canon EF 16-35mm f/2.8L USM	Sigma 17-35mm f/2.8-4 EX DG Aspherical HSM
Weight (g)	600	560
Aperture (f)	2.80 - 22.00	2.80 - 22.00
Diaphragm Blades	7	8
Diagonal Angle of View (degree)	63.00 - 108.20	63.40 - 103.70
Lens Construction	13 elements in 10 groups, including 3 aspherical and 2 UD elements	16 elements in 13 groups, including 2 aspherical and 1 SLD elements
Diameter (mm)	83.5	83.5
Focus Details	Inner focusing; full-time manual focus and USM;	Internal Focus; HSM with full-time manual override